In what could be one of the worst failures of the Pentagon’s program to arm Syrian rebels, several bases with American weapons, armored vehicles and US-trained fighters were plundered by Al-Nusra Front. The jihadists and “moderate rebels” are blaming each other for the attack.

Division 13 of the Free Syrian Army (FSA), which had received both US weapons and training, on Sunday said it was attacked by Al-Nusra Front militants – radical Islamist fighters affiliated with Al-Qaeda. The jihadists looted the FSA group’s depots in the town of Maarrat Al-Nuuman in Syria’s Idlib province.

Though it has widely been reported that weapons and dozens of Division 13 fighters have been captured, there are conflicting accounts of how much the jihadists could actually carry. Some media reports claimed that the haul included US-supplied TOW anti-tank missiles, firearms and ammunition, and unspecified armored vehicles, including a tank. The rebel group’s chief has denied they have lost anti-tank missiles, telling AFP that only “light weapons” have been taken.

Moreover, up to 40 Division 13 fighters have been taken hostage and four killed, the Syrian Observatory for Human Rights has said, though the remote “sources on the ground” routinely cited by the UK-based organization are often hard to verify.

Adding to the rebel group’s dismay, Al-Nusra was also the first to release an online statement – blaming Division 13 for provoking the attack. In turn, the rebels denied attacking Al-Nusra and accused them of an unexpected armed assault on a checkpoint, set up at the request of the local population.

The reason reportedly given by the US-backed group as to why they couldn’t have attacked the Islamists? Too weak for the job.

The feud between the militant factions, once close allies in fighting Syrian President Bashar Assad’s forces, has been brewing for some time, according to AP. Al-Nusra has recently suppressed demonstrations and arrested protesters in the city of Idlib, and reportedly replaced the tricolor of the Syrian rebels with the black Al-Qaeda flag there.

On Friday, in Maaret al-Numan, motorcyclists waving the black flag of Al-Nusra threatened to fire on a protest, shouting “Allahu akbar” or “God is greatest.”

Interestingly, Al-Nusra has a history of looting US-backed opposition forces: last summer, jihadists kidnapped members of the US-trained Division 30, while in September a whole stock of US-supplied weapons and hardware was captured.

The Pentagon’s failed rebel-training program was canceled in October, after dozens of US-trained rebels abandoned Division 30 and handed the weapons they had been supplied to Al-Nusra upon crossing from Turkey into Syria.

However, the head of US Central Command, General Lloyd Austin, proposed to restart training for Syria’s so-called “moderate” rebels.

A month later, the US State Department admitted that some of the “moderates” had been successfully recruited by Al-Nusra in Syria.